In a third generation partnership project (3GPP) wireless communication system, signaling radio bearers (SRBs) are used to maintain a connection, (i.e., an RL), between a WTRU and a Universal Terrestrial Radio Access Network (UTRAN). When reception of the physical channel connecting the WTRU and Node-B is below a quality threshold or can not be detected, (i.e., the physical channel that allows for signaling information to be exchanged between the WTRU and UTRAN has failed), an RL failure is declared, and the WTRU and the UTRAN initiate procedures to reestablish the connection between the WTRU and the UTRAN.
In order to realize the loss of the SRBs and take a proper action, the WTRU and the UTRAN constantly monitor for an occurrence of an RL failure. A primary objective of the RL failure detection procedure is to detect failure of the transport channels (TrCHs) and physical channels to which the SRBs are mapped.
In the 3GPP wireless communication system, SRBs are mapped to dedicated transport channels (DCHs) which are in turn mapped to dedicated physical channels (DPCHs). A DPCH comprises a dedicated physical control channel (DPCCH) and a dedicated physical data channel (DPDCH).
The criteria to detect the status of the DPCHs and DCHs includes estimation of the DPCCH quality, (and comparison to a predetermined threshold), and/or collection of statistics of correct reception of data packets on a DPCH based on cyclic redundancy check (CRC). When the criteria are met, the WTRU and the UTRAN invoke a procedure to release and reestablish the connection between the WTRU and the UTRAN.
In the 3GPP wireless communication system, both continuous services, (e.g., speech), and interactive services, (e.g., web browsing), are supported. Dedicated channels are efficient for supporting continuous services, while shared channels are efficient for supporting interactive services. The shared channels provide more efficient use of radio resources and improved quality of service (QoS) for interactive services. However, when the service is mapped to shared channels, the use of dedicated channels for SRBs is inefficient since the traffic requirement is not continuous.
In 3GPP wireless communication systems, HSUPA and HSDPA primarily utilize high speed shared channels for services that do not require continuous channel allocations. These channels utilize fast physical and medium access control (MAC) layer signaling between the WTRU and the Node-B for channel assignment and hybrid-automatic repeat request (H-ARQ) for efficient and fast recovery of failed transmissions.
If the SRBs are supported by either HSUPA or HSDPA channels rather than dedicated channels, it is possible that SRBs may fail, even though dedicated channels are still operating. Furthermore, the criteria to detect the dedicated channel failure may not be met even though the HSUPA or HSDPA channels supporting the SRBs are not operating. In this case, RL failure will not be detected even though the SRBs have already lost connectivity.